RFC 3497 (rfc3497) - Page 2 of 12

RTP Payload Format for Society of Motion Picture and Television Engineers (SMPTE) 292M Video

RFC 3497        RTP Payload Format for SMPTE 292M Video       March 2003


   It is to be noted that SMPTE 292M streams have a constant high bit
   rate and are not congestion controlled.  Accordingly, use of this
   payload format should be tightly controlled and limited to private
   networks or those networks that provide resource reservation and
   enhanced quality of service.  This is discussed further in section 9.

   This memo only addresses the transfer of uncompressed HDTV.
   Compressed HDTV is a subset of MPEG-2 [9], which is fully described
   in document A/53 [10] of the Advanced Television Standards Committee.
   The ATSC has also adopted the MPEG-2 transport system (ISO/IEC
   13818-1) [11].  Therefore RFC 2250 [12] sufficiently describes
   transport for compressed HDTV over RTP.

2.  Overview of SMPTE 292M

   A SMPTE 292M television line comprises two interleaved streams, one
   containing the luminance (Y) samples, the other chrominance (CrCb)
   values.  Since chrominance is horizontally sub-sampled (4:2:2 coding)
   the lengths of the two streams match (see Figure 3 of SMPTE 292M
   [1]).  In addition to being the same length the streams also have
   identical structures: each stream is divided into four parts, (figure
   1): (1) start of active video timing reference (SAV); (2) digital
   active line; (3) end of active video timing reference (EAV); and (4)
   digital line blanking.  A SMPTE 292M line may also carry horizontal
   ancillary data (H-ANC) or vertical ancillary data (V-ANC) instead of
   the blanking level; Likewise, ancillary data may be transported
   instead of a digital active line.

   The EAV and SAV are made up of three 10 bit words, with constant
   values of 0x3FF 0x000 0x000 and an additional word (designated as XYZ
   in figure 2), carrying a number of flags.  This includes an F flag
   which designates which field (1 or 2) the line is transporting and
   also a V flag which indicates field blanking.  Table 1, further
   displays the code values in SAV and EAV.  After EAV, are two words,
   LN0 and LN1 (Table 2), that carry the 11 bit line number for the
   SMPTE 292M line.  The Cyclic Redundancy Check, CRC, is also a two
   word value, shown as CR0 and CR1 in figure 2.

      +------------+-----------------------+-----+---------------------+
      |            | Digital Line Blanking |     | Digital Active Line |
      | EAV+LN+CRC | (Blanking level or    | SAV |  (Active Picture or |
      |            |  Ancillary Data)      |     |   Ancillary Data)   |
      +------------+-----------------------+-----+---------------------+

                     Figure 1. The SMPTE 292M line format.






Gharai, et al.              Standards Track